Impression control mechanism for a typewriter or similar machine

ABSTRACT

Impression control mechanism for regulating the impact velocity of a single element type carrier against a platen. The support for the type carrier is driven about a pivot by a cam to effect printing. The cam acts through one end of a control lever which end in turn supports and acts directly on a pin located on and spaced from the type carrier support pivot. The control lever is pivoted at its opposite end to an adjusting lever which is itself pivoted to move the control lever pivot and through its end acting on the pin to shift the type carrier support about its pivot establishing the rest position of the type carrier relative to the platen thereby determining the impact velocity of the type carrier.

United States Patent 1 Nowak et al.

[ IMPRESSION CONTROL MECHANISM FOR A TYPEWRITER OR SIMILAR MACHINE [75]Inventors: Gerald Nowak, Bienrode; Herbert Decker, Lauf, both of Germany[73] Assignee: Triumph Werke Nurnberg A. G.,

Nurnberg, Germany [22] Filed: Mar. 1, 1974 [21] Appl. No.1 447,229

Related US. Application Data [63] Continuation of Ser, No, 277,591, Aug3, 1972,

abandoned.

[30] Foreign Application Priority Data Aug. 7, 1971 Germany 2139650 [52][1.8. Cl 197/55; 197/18 [51] Int. Cl B4lj H60 [53] Field of Search74/53, 539; 197/16, 17, 197/55, 18

[56] References Cited UNITED STATES PATENTS 213,553 3/1879 Eastwood74/569 2,879,876 3/1959 Palmer et a1 H 197/16 2,926,768 3/1960 Becker eta1 197/55 X 1 June 10, 1975 3,263,511 8/1966 Wellstein 74/53 3,330,3987/1967 Hylan 197/16 ()THER PUBLlCATlONS IBM Customer EngineeringReference Manual" for Selectric l/O Keyboard Printer, pgs. (2-40 2-42).

Primary ExaminerEdgar S. Burr Assistant Examiner--Paul .1 HirschAttorney, Agent, or Firm-Joseph R. Spalla 57] ABSTRACT Impressioncontrol mechanism for regulating the impact velocity of a single elementtype carrier against a platen. The support for the type carrier isdriven about a pivot by a cam to effect printing. The cam acts throughone end of a control lever which end in turn supports and acts directlyon a pin located on and spaced from the type carrier support pivot. Thecontrol lever is pivoted at its opposite end to an adjusting lever whichis itself pivoted to move the control lever pivot and through its endacting on the pin to shift the type carrier support about its pivotestablishing the rest position of the type carrier relative to theplaten thereby determining the impact velocity of the type carrier.

3 Claims, 2 Drawing Figures IMPRESSION CONTROL MECHANISM FOR ATYPEWRITER OR SIMILAR MACHINE This is a continuation of copending U.S.application Ser. No. 277,591, tiled Aug. 3, 1972, now abandoned.

This invention relates to an impression control mechanism in a powerdriven typewriter or similar business machine for regulating theintensity with which a type element impacts against a recording medium,and more particularly to an impression control mechanism for regulatingthe impact intensity ofa single element typewriter in which the typeelement or carrier is mounted on a carriage for movement past therecording medium.

In a typewriter or similar business machine in which printing iseffected by a type element or type character impacting against therecording medium, an impression control mechanism is usually provided tocontrol the intensity with which the type character strikes against therecording medium so as to control the density or outline of thecharacter thus formed on the recording medium. In a conventional singleelement typewriter all of the type characters are carried on a generallysphere-like member which undergoes a common stroke for each character tobe printed, and accordingly only a single impression control mechanismis necessary to vary the intensity of impact resulting from the singleprinting stroke. However, since the printing element is carried along aline of type by a carriage during successive printing operations, it isnecessary for the impression control mechansim to likewise be mounted onthe carriage for movement with the single element printer.

In the typical single element printer, the type element is mounted on apivotally supported rocker, and printing is effected by pivoting therocker to move the type element from a normal position to a printingposition where it impacts against a paper platen. Usually, this isaccomplished by means of a cam acting on the rocker through a camfollower which is pivotally supported with one end of the cam followerengaging the rotatably driven cam, and with the other end connected tothe rocker for moving it to the printing position. Variation of theimpacting intensity may be accomplished by shifting the pivot point ofthe cam follower, as shown for example in German Pat. No. l,078,59l, andUS. Pat. Nos. 2,926,768 and 2,879,876. Alternatively, the point ofengagement between the cam follower and the rocker member may be variedas shown, for example, on Page 38 of the IBM Selectric Instructionmanual, January 1966. However, in the latter example the adjustingmechanism, which is in the form of a pivotally supported lever having apin engaging the cam follower, is carried on the rocker with theprinting element, and such an arrangement adds an undesirable amount ofmass which must be moved during each printing stroke. In eitherinstance. the mechanism for varying the impact intensity of a typecharacter against the recording medium is usually difficult to adjust,and composed of an undesirable number of parts.

Accordingly, an object of the present invention is to provide animpression control mechanism for regulating the impact intensity ofatype character against a recording element which is composed of a fewparts which are easy to manufacture and require a minimum of space.

Another object of the invention is to provide an impression controlmechanism in which the impact intensity of a type character striking arecording medium may be easily regulated.

A further object of the invention is to provide an impression controlmechanism which minimizes the number of parts movable during a printingstroke so as to minimize the mass which must be moved and hence theinertia which must be overcome to impact a type character against arecording element.

Still other objects, features and advantages of the present inventionwill become apparent to those skilled in the art from a reading of thefollowing detailed description of the preferred embodiment of theinvention, taken in conjunction with the accompanying drawings, wherein:

FIG. I is a partial diagrammatic view of a printing arrangement havingan impression control mechanism constructed in accordance with thepresent invention, and showing the relative position of the parts of thearrangement when the impression control mechanism is placed at onesetting; and

FIG. 2 shows the printing arrangement of FIG. I with the impressioncontrol mechanism moved to another setting to show the change in therelative position of the parts.

Referring now in detail to the figures in the drawing, there is shown atypewriter printing arrangement, generally indicated 11, for printingtype characters or other symbols on a recording medium, not shown, whichmay desirably be located on a platen 13. The type characters or othersymbols to be printed, not shown, are formed on a generally sphericalelement 15 of a type carrier, generally indicated 17, and the typecarrier 17 is supported for a movement from a normal or rest position toa printing position at the platen 13. As is conventional, printing iseffected by impacting a selected type character against the recordingmedium and the type carrier 17 is driven in a printing movement to theprinting position by a drive means, generally indicated 19, which maydesirably be power operated by a motor, not shown. The printingarrangement is supported on a carriage 21 for movement along a line oftype past the platen l3, and the carriage is mounted on a sleeve 23which is slidably carried by a shaft 25 for movement past the platen 13.The recording medium, the type characters, the motor for operating thedrive means 19 as well as the other portions of the typewriter are notshown since they form no part of the present invention and may bedesirably conventional.

As shown, the type carrier 17 includes a rocker or base element 27 whichis supported for pivotal movement by bolts 29 or other conventionalmeans which may be suitably secured to the carriage 21. The drive means19 is in the form of an eccentric cam 31 carried on a rotatably drivendrive shaft 33 which undergoes a single revolution during each printingoperation. As the cam 31 is rotatably driven through a singlerevolution. the type carrier 17 undergoes a printing movement from thenormal position to the printing position to impact a type characteragainst the recording medium to effect printing. After printing, thetype carrier 17 is returned to the normal position by the urging of aresilient biasing means 35 as permitted by the rotational movement ofthe cam 31.

To control the intensity with which a type character impacts against thepaper platen I3, and hence the impression on the recording medium, theprinting arrangement II is provided with impact regulating means in theform of an impression control mechanism, gener ally indicated byreference numeral 37, for selectively controlling the force imparted tothe type carrier 17 during a printing movement by the operation of thedrive means 19. As shown. the impression control mechanism 37 includes apivotally supported control member 39 having a projecting portion 41 forengaging the camming surface of the eccentric cam 31 and having anotherportion 43 for engaging the type carrier 17. The other portion 43 is inthe form of a slot extending from adjacent the projection 41 toward thepivotal sup port of the control member 39, and the slot receives a pin45 which is suitably secured to an extension 47 from the rocker base 27of the type carrier 17. The projection 41 of the control member 39 isurged into engagement with the cam 31 by the resilient biasing means 35which may be in the form of a spring stretched between the controlmember 39 and the carriage 21 and suitably secured thereto As the cam 31rotates past the projection 41 during a printing operation, a drivingmovement is transmitted to the type carrier 17 through the projection 41at the free end of the control member 39 whose upper portion 43 actsagainst pin 45 on the type carrier rocker element 27, driving the typecarrier toward the platen 13.

lnasmuch as the cam 31 imparts the same movement to projection 41 eachprinting cycle, the impact velocity of the type carrier 15 is determinedby establishing a rest position of the type carrier 15 and its base orsupport 27 closer to or away from the platen 13. The rest position isestablished by moving the drive pin 45 upwardly from FIG 1 to FIG 2along portion 43 of the control member 39 and incident to its leftwardmovement. Thus, to selectively vary the impact velocity of the typecarrier against the platen 13. The impression control mechanism 37includes means in the form of an adjusting member 49 for moving thecontrol member 39 with portion 43 acting against pin 45 to pivot rocker27 about its pivot 29. As shown, the control member 39 is pivotallysupported on the adjusting member 49 by suitable means, for example apivot pin 51, and the adjusting member 49 is pivotally supported on thecarriage 21 by suitable means, for example a pin 52. By pivotally movingthe adjusting member 49 from one position to another position, as shownfor example in FIGS, 1 and 2, the control member 39 is moved to theleft, reducing the distance between control member pivot 51 and pin 45,and, its free end constrained by the cam 31, causing portion 43 to acton pin 45 and rock the type carrier rocker 27 counterclockwise about itspivot 29 to vary the distance between the platen 13 and the type carrier17 while in the normal position. Since very little force is exerted onthe adjusting member 49 during a printing operation, the adjustingmember 49 may be held in a selected position by suitable detents.

In a printing operation. the type carrier 17 is driven from the normalposition to the printing position to impact the selected type characteragainst a recording medium on the platen 13 by rotatably driving theeccentric cam 31 through a single revolution. As the lobe of the cam 31passes the projection 41 of the control member 39, the driving movementprovided by the rotatably driven cam 31 imparts a printing movement tothe type carrier 17. The type carrier 17 is driven against the urging ofthe spring 35, and after impact the spring 35 again urges the typecarrier 17 to return to the normal position as permitted by therotational movement of the cam 31. The intensity with which the typecarrier impacts against the platen 13 is determined by the position ofthe adjusting member 49 which may be pivotally moved to a selectedposition to shift the control member 39 to the left or right, shorteningor lengthening the distance between pivot 51 and pin 45, whereby itsfree end, constrained by cam 31, will cause portion 43, supporting pin45, either to raise or lower pin 45 about rocker pivot 29 thus adjustingthe rest position of the type carrier 15 relative to the platen 13. FIG.2 shows the type carrier 15 initially positioned closer to the platen13. As the angle of drive imparted by the cam 31 is constant, the typecarrier 15 will be driven closer to the platen and strike with a greatervelocity.

While only a single preferred embodiment of the invention has beenillustrated and described, it will be apparent to those skilled in theart that various improvements and modifications may be made.Accordingly, it is to be understood that this invention is not to belimited by the illustrative embodiment, but only by the scope and spiritof the appended claims What is claimed is:

1. A single element printing machine comprising a frame,

a platen,

a type carrier having a plurality of type characters formed thereon,

means supporting said type carrier about a pivot axis on said framewhereby said type carrier can be driven from a rest position toward saidplaten to impact a selected character against said platen,

said support means having a pin thereon spaced from said pivot axis,

a drive cam rotatably mounted on said frame for driving said typecarrier support means about its pivot axis,

a control member having one end located between said cam and said pin,

said one end supporting said pin and establishing a rest position ofsaid type carrier support means,

and an operator controlled adjusting member for determining the impactvelocity of said type carrier against said platen,

said control member being pivotally supported at its other end on saidadjusting member at a point. said point and said pivot axis being onopposite sides of said pin,

said adjusting member being pivotally supported on said frame wherebypivotal movement thereof shifts said control member between said cam andsaid pin to rock said type carrier support means about its pivot axis toestablish a rest position of said type carrier closer to or farther fromsaid platen.

2. A printing machine as recited in claim 1, including spring meansbiasing said control member into contact with said cam.

3. A printing machine as recited in claim 2, wherein said one end ofsaid control member is forked to receive said pin.

1. A single element printing machine comprising a frame, a platen, atype carrier having a plurality of type characters formed thereon, meanssupporting said type carrier about a pivot axis on said frame wherebysaid type carrier can be driven from a rest position toward said platento impact a selected character against said platen, said support meanshaving a pin thereon spaced from said pivot axis, a drive cam rotatablymounted on said frame for driving said type carrier support means aboutits pivot axis, a control member having one end located between said camand said pin, said one end supporting said pin and establishing a restposition of said type carrier support means, and an operator controlledadjusting member for determining the impact velocity of said typecarrier against said platen, said control member being pivotallysupported at its other end on said adjusting member at a point, saidpoint and said pivot axis being on opposite sides of said pin, saidadjusting member being pivotally supported on said frame whereby pivotalmovement thereof shifts said control member between said cam and saidpin to rock said type carrier support means about its pivot axis toestablish a rest position of said type carrier closer to or farther fromsaid platen.
 2. A printing machine as recited in claim 1, includingspring means biasing said control member into contact with said cam. 3.A printing machine as recited in claim 2, wherein said one end of saidcontrol member is forked to receive said pin.